Field
The present disclosure relates generally to medical devices, and specifically to surgical instruments and methods for performing spinal procedures.
Background
The spine is critical in human physiology for mobility, support, and balance. The spine protects the nerves of the spinal cord, which convey commands from the brain to the rest of the body, and convey sensory information from the nerves below the neck to the brain. Even minor spinal injuries can be debilitating to the patient, and major spinal injuries can be catastrophic. The loss of the ability to bear weight or permit flexibility can immobilize the patient. Even in less severe cases, small irregularities in the spine can put pressure on the nerves connected to the spinal cord, causing devastating pain and loss of coordination.
The spinal column is a bio-mechanical structure composed primarily of ligaments, muscles, bones, and connective tissue that forms a series of vertebral bodies stacked one atop the other and intervertebral discs between each vertebral body. The spinal column provides support to the body and provides for the transfer of the weight and the bending movements of the head, trunk and arms to the pelvis and legs; complex physiological motion between these parts; and protection of the spinal cord and the nerve roots.
The stabilization of the vertebra and the treatment for spinal conditions is often aided by a surgically implanted fixation device which holds the vertebral bodies in proper alignment and reduces the patient's pain and prevents neurologic loss of function. Spinal fixation is a well-known and frequently used medical procedure. Spinal fixation systems are often surgically implanted into a patient to aid in the stabilization of a damaged spine or to aid in the correction of other spinal deformities. Existing systems often use a combination of rods, plates, pedicle screws, bone hooks, locking screw assemblies, and connectors, for fixing the system to the affected vertebrae. The system components may be rigidly locked together to fix the connected vertebrae relative to each other, stabilizing the spine until the bones can fuse together.
A spinal rod is often anchored to two or more vertebrae to immobilize the spine between the two vertebrae. To reduce tissue trauma and opportunity for infection, there have been attempts to develop minimally invasive approaches. Sometimes, minimally invasive rod insertion includes advancing the rod towards the anchors through a guide and then angling a rod inserter to rotate the rod to a position that is in line with the rod channels in the anchors. Because of the limited space available to maneuver the rod, the longer the rod is the more challenging the insertion becomes. This creates two problems. The awkwardness in guiding a rod of sufficient length to connect the desired vertebrae can result in errors, such as passing the rod above the fascia. It also results in limiting the lengths of the rod that can be inserted in a minimally invasive manner.
Consequently there is a need in the art for a way to insert longer rods below the patient's fascia in a minimally invasive manner.